diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 20f0873..a4b3abf 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -32,6 +32,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 20
+          cache: npm
       - run: npm audit --audit-level=high
 
   commitlint:
@@ -52,7 +53,7 @@ jobs:
           cache: npm
 
       - name: Install dependencies
-        run: npm install
+        run: npm ci
 
       # Lint every commit in the PR from the merge base to HEAD.
       - name: Lint commit messages
@@ -93,20 +94,14 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      # ── Node / npm cache (#130) ──────────────────────────────────────────
       - uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
-      - run: npm install
-      - run: npm run lint
-      - run: npm run typecheck
-      - run: npm run build
-      - run: npm test -- --coverage
-      - run: npm run test:e2e
-          node-version: 20
           cache: npm
 
       - name: Install dependencies
-        run: npm install
+        run: npm ci
 
       # ── Prisma ──────────────────────────────────────────────────────────────
       - name: Validate Prisma schema
@@ -135,3 +130,21 @@ jobs:
 
       - name: E2E tests
         run: npm run test:e2e
+
+  # ── Docker build verification (#131) ──────────────────────────────────────
+  # Ensures every push that changes application code doesn't silently break
+  # the Dockerfile. Image publishing to a registry can be wired up separately
+  # once registry credentials are in place.
+  docker:
+    name: Docker – build verification
+    runs-on: ubuntu-latest
+    needs: backend
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: false
+          tags: vortex-backend:ci
diff --git a/README.md b/README.md
index 99d52f7..958575e 100644
--- a/README.md
+++ b/README.md
@@ -123,6 +123,29 @@ flags to override them.
 
 ---
 
+## Supported chains
+
+`SupportedChain` in `src/intents/intents.types.ts` lists seven chains.
+The table below clarifies which are **live** (real integration exists today)
+versus **planned** (schema/token data in place, on-chain settlement pending).
+
+| Chain | Status | Notes |
+|-------|--------|-------|
+| **Stellar** | ✅ Live | Soroban RPC reads (`/api/v1/chain/*`), signing service, settlement design in progress |
+| Ethereum | 🔲 Planned | Token registry populated; on-chain integration not yet implemented |
+| Base | 🔲 Planned | Token registry populated; on-chain integration not yet implemented |
+| Polygon | 🔲 Planned | Token registry populated; on-chain integration not yet implemented |
+| Arbitrum | 🔲 Planned | Token registry populated; on-chain integration not yet implemented |
+| Optimism | 🔲 Planned | Token registry populated; on-chain integration not yet implemented |
+| Avalanche | 🔲 Planned | Token registry populated; on-chain integration not yet implemented |
+
+> **Contributor note:** EVM chains are accepted in the intent DTO and stored
+> in-memory, but no on-chain settlement or bridging logic is wired up yet.
+> See [`docs/architecture/onchain-settlement.md`](./docs/architecture/onchain-settlement.md)
+> for the target design.
+
+---
+
 ## Roadmap
 
 - [x] **Soroban RPC reads** — health/ledger/network/account lookups via `/api/v1/chain/*`
diff --git a/src/intents/dto/create-intent.dto.ts b/src/intents/dto/create-intent.dto.ts
index f7c7f5c..ea8a9c3 100644
--- a/src/intents/dto/create-intent.dto.ts
+++ b/src/intents/dto/create-intent.dto.ts
@@ -1,19 +1,9 @@
 import { IsIn, IsInt, IsOptional, IsString, Matches, Max, Min, MinLength } from "class-validator";
 import { ApiProperty, ApiPropertyOptional } from "@nestjs/swagger";
-import { SupportedChain } from "../intents.types";
+import { SUPPORTED_CHAINS, SupportedChain } from "../intents.types";
 import { IsValidAddress } from "../../common/validators/is-valid-address.validator";
 import { IsValidDeadline } from "../../common/validators/deadline.validator";
 
-const SUPPORTED_CHAINS: SupportedChain[] = [
-  "stellar",
-  "ethereum",
-  "base",
-  "polygon",
-  "arbitrum",
-  "optimism",
-  "avalanche",
-];
-
 export class CreateIntentDto {
   @ApiProperty({ description: "Stellar address of the user creating the intent" })
   @IsString()
diff --git a/src/intents/intents.types.ts b/src/intents/intents.types.ts
index b16cfe1..5c5c79b 100644
--- a/src/intents/intents.types.ts
+++ b/src/intents/intents.types.ts
@@ -1,11 +1,20 @@
-export type SupportedChain =
-  | "stellar"
-  | "ethereum"
-  | "base"
-  | "polygon"
-  | "arbitrum"
-  | "optimism"
-  | "avalanche";
+/**
+ * Single source of truth for every chain the protocol recognises.
+ * `SupportedChain` is derived from this tuple so all three consumers
+ * (intents.types.ts, create-intent.dto.ts, tokens.data.ts) stay in sync
+ * automatically — see issue #128.
+ */
+export const SUPPORTED_CHAINS = [
+  "stellar",
+  "ethereum",
+  "base",
+  "polygon",
+  "arbitrum",
+  "optimism",
+  "avalanche",
+] as const;
+
+export type SupportedChain = (typeof SUPPORTED_CHAINS)[number];
 
 /**
  * A single entry in the append-only audit log for an intent.
diff --git a/src/intents/supported-chains-sync.spec.ts b/src/intents/supported-chains-sync.spec.ts
new file mode 100644
index 0000000..913280c
--- /dev/null
+++ b/src/intents/supported-chains-sync.spec.ts
@@ -0,0 +1,42 @@
+/**
+ * Regression guard for issue #128.
+ *
+ * Ensures that:
+ *  1. CreateIntentDto's @IsIn validator uses the same canonical list as
+ *     `SupportedChain` (guaranteed structurally after the refactor — this
+ *     test documents the contract).
+ *  2. Every EVM chain declared in SUPPORTED_CHAINS has a corresponding entry
+ *     in tokens.data.ts so the token registry never silently lags behind.
+ */
+import { SUPPORTED_CHAINS } from "./intents.types";
+import { SUPPORTED_TOKENS } from "../tokens/tokens.data";
+
+describe("SUPPORTED_CHAINS sync guard (#128)", () => {
+  it("SUPPORTED_CHAINS contains at least 'stellar' and at least one EVM chain", () => {
+    expect(SUPPORTED_CHAINS).toContain("stellar");
+    const evmChains = SUPPORTED_CHAINS.filter((c) => c !== "stellar");
+    expect(evmChains.length).toBeGreaterThan(0);
+  });
+
+  it("every EVM chain in SUPPORTED_CHAINS has token entries in tokens.data.ts", () => {
+    const evmChains = SUPPORTED_CHAINS.filter((c) => c !== "stellar");
+    const missingChains: string[] = [];
+
+    for (const chain of evmChains) {
+      const tokens = SUPPORTED_TOKENS[chain];
+      if (!tokens || tokens.length === 0) {
+        missingChains.push(chain);
+      }
+    }
+
+    expect(missingChains).toEqual([]);
+  });
+
+  it("tokens.data.ts has no extra EVM chains that are not listed in SUPPORTED_CHAINS", () => {
+    const tokenChains = Object.keys(SUPPORTED_TOKENS);
+    const unrecognised = tokenChains.filter(
+      (c) => !(SUPPORTED_CHAINS as readonly string[]).includes(c),
+    );
+    expect(unrecognised).toEqual([]);
+  });
+});